In the development of counter top appliances for the kitchen, it has been found that to perform the various processes such as mixing, blending, chopping, juicing, and the like, which are necessary to prepare many of the foods now consumed in the home, there is a preference for the multi-purpose appliance. Such appliances are of the type which may be easily converted to perform a number of different functions by interchangeably mounting separate appliance accessories to a common base or power unit. Their advantages are apparent, particularly where the storage or work areas of the kitchen are modestly sized making it difficult to use a separate appliance for each operation.
It has further been found that in order for the multi-purpose appliance to be favorably received by the consumer it must be economically priced and must perform its functions substantially as effectively as the appliances available for performing the same functions separately. In this regard, significant difficulties exist in providing the versatility needed in the areas of power, torque, and speed of operation, to incorporate the many functions into a single and efficient appliance. An example of a multi-purpose appliance having such capabilities is disclosed in Ernster et al, U.S. Pat. Nos. 3,951,351 and 4,071,789.
The multi-purpose appliances of the type disclosed in the above-cited Ernster et al patents have proved to be economical and quite effective in the mixing, blending, chopping and juicing of foods. The power unit is provided with a variable speed control so that a wide range of speeds are available for the various accessary appliances. Mixing or beating of food ingredients is accomplished by a mixing head which comprises a gear train for driving appropriate beater members in an arrangement which appears somewhat similar to conventional mixing appliances. Since the speed of the beaters may be selectively controlled by adjusting the power of the base unit, a number of mixing tasks may be performed with desirable results.
Notwithstanding the facility with which these appliances operate, it would be desirable to increase their versatility still further. The trends in food preparation today are such that an appliance is needed which performs all of the aforementioned functions, and in addition, is suitable for the kneading of dough. With the increasing preference for natural foods and foods of a homemade freshness and quality, it is becoming more common to find baked goods such as bread, pastries, and the like, being prepared in the home. The conventional multi-purpose appliance has been relatively unsuccessful in coping with this additional task. Although conventional dough hooks, for example, could be used with such appliances as the type disclosed in the above-mentioned Ernster et al patents, difficulties arise, again by virtue of the specific mechanical requirements of the process, making present-day multi-purpose appliances generally inefficient when used for kneading bread dough.
To understand the specific requirements of the kneading process, it is necessary to briefly consider the technique involved in making dough with the use of an electric mixing appliance. A preferred method of making dough begins by mixing the ingredients first with only a small amount of flour. This allows for a uniform distribution of yeast cells throughout the dough and permits one to use relatively high speed beaters while the dough is thin in consistency. It is then necessary to add the balance of the flour by kneading in order to assure that this uniformity of yeast distribution is maintained. Although the kneading can be done by hand, it is preferred that an electric mixer, equipped with conventional dough hooks, be used. In order to do so, however, it is necessary that the speed of the mixer be reduced so that the dough can be turned and folded as it becomes thickened in consistency. The problem involved is that by lowering the speed of the normal multi-purpose appliance, the power of the drive unit is correspondingly reduced and the dough hooks then lack sufficient torque to maintain a steady kneading action. In addition, though this problem could be overcome by constructing an appliance having a more powerful drive unit, such a solution would greatly increase the physical size and cost of the appliance, and would render it substantially less desirable to the consumer.
Other multi-purpose appliances are disclosed in the Strauss et al U.S. Pat. No. 2,278,187; in Schottle U.S. Pat. No. 2,801,545; and in Moore U.S. Pat. No. 2,685,435; which each show combination blender and mixer appliances that could be selectively used for the kneading of dough. It would be desirable, however, to provide a more effective multi-purpose appliance which overcomes the aforementioned difficulties without sacrifice of its economy and convenience.